In a Rolling Stoneprofile, Winter recalled how he had begun using Tweedy's recordings, both solo and with sons Spencer and Sam Tweedy, as temp music while assembling footage for the film.

"I normally temp with movie scores, but I was finding that I was using Tweedy music — mostly solo and family stuff," Winter explained. "So I thought, 'Well, hell, why don't I just ask [the Tweedys] to do the music?' I also was really drawn to a band made up of a father and his sons, as family and those relationships play such a big part in our story."

Winter then send the Tweedys a rough cut of the film, explaining why their music felt to him like a perfect fit.

"The soundtrack has a lot of emotion and intimacy," he said. "The movie is very intimate and personal, and I wanted the music to feel like more than just score. I wanted it to feel like another character in the movie. Jeff, Spencer and [Jeff's other son] Sam have so much personality in their music, so it just adds an enormous amount to the doc."

Of Showbiz Kids, Spencer said, "It's a pretty weird thing that exists in the world that young people can become famous. We haven't experienced any level of fame anywhere near the subjects of the film, but we were excited that Alex was examining that and potentially helping people understand what those experiences can be like."

The Tweedys were also excited at the challenge of making music differently.

As Spencer recalled, "It was really a new way of working and it was really rewarding. Especially when it comes to the work that Sammy does with synthesizers. We don't always have an outlet for drone things or sequenced things, so it was an opportunity to combine some synthesized stuff with acoustic instruments. It was a challenge we're all grateful that Alex gave us."

Sam added, "I think it's interesting how it's not going to be the 'Tweedy sound'; it's a new Tweedy sound. I'm excited that we're using that moniker for the score and yet it will have only the kernel of Tweedy-ness and it will sound totally and utterly different from that."

Currently in production, Showbiz Kids will feature interviews with prominent actors who began their careers as children. The film, produced by Bill Simmons (30 for 30), will air on HBO this fall.

"I experienced all the highs and lows that one associates with this world and felt that there had never been a film that thoroughly explored both the personal impact of this life and the broader social implications," Winter told Rolling Stone. "This isn't a salacious examination, but an intimate journey through the history of the entertainment industry through the eyes of its working kids."

At this point, it's unclear if Showbiz Kids will get a proper soundtrack release.